Catalytic hydrocarbon conversion activity determination process



United States Patent 3 169,831 CATALYTIC HYDROCARBON CONVERSIO ACTIVITYDETERMINATION PROCESS Ralph J. Bertolacini, Chesterton, Ind., assignorto Standard Oil Company, Chicago, 111., a corporation of Indiana NoDrawing. Original application Mar. 15, 1960, Ser. No. 15,035. Dividedand this application Nov. 29, 1961, Ser. No. 155,823

4 Claims. (Cl. 23-230) This invention relates to a method for processinga composite comprising one or more noble metals and a refractoryinorganic material.

Composites containing one or more noble metals admixed with a refractoryinorganic material such as metal oxides or silicates arefrequently usedin the chemical and petroleum industries, e.g., the platinum supportedon alumina catalysts now usedextensively in catalytic reforming. In bothresearch and commercial operations using these composites, it isfrequently necessary to determine their hydrocarbon conversion activity,not only prior to their use but also after they have become partially orcompletely deactivated.

The noble metal portion of these composites is frequently small, on theorder of one weight percent. Hydrocarbon conversion activity, however,is not a direct func- I stantially all of the metal orginally in thecomposite. The

tion of the weight fraction of the composite which is a noble metal.Furthermore, the hydrocarbon conversion activity of a particularcomposite of specific noblemetal content is not constant, but variesaccording to the conditions to which that composite has been subjected.Ac-

cordingly, it has been necessary heretoforeto determine hydrocarbonconversion activity of a composite by conducting hydrocarbon conversionOperationa'either commercially or in a pilot plant under conditionssimulating those of commercial operatiom Even pilot plant operationsconducted for this purpose are expensive and frequently too timeconsuming-for research purposes or for process control. i i v l Althoughthe noble metal portion of the-catalytic composites is small, the valuethereof is sufiiciently great to justify its extraction from 'adeactivated composite and, with particular reference toplatinun-nco'ntaining reforming catalysts, this is generally done, Incommercial practice' a noble metal is recovered by dissolvingboth' thenoble metal'and its supporting carrier in a solvent. Inasmuch as boththe noble metal and the supporting carrier are takeninto'solution, thedissolving procedure does not accomplish any increase in theconcentration of' the noble-metal relative to the supporting carrier,nor any separation of the metal from afcarrier. 'It is then necessary torecover the metal from a solution of which it constitutes a very smallfraction.

A method has now been-discovered for processing with acetyl'ace tone' acomposite comprising a noblemetal and a refractory inorganic material,wherebythe metal in a form soluble in acetylacetone is separated fromany of the metal in-afforminsoluble in' acetylacetones This methodcomprises contacting the composite with-acetylacetone in the liquidphase for a time sutlicient to dissolve therein any of the metal in thecomposite which exists in' a form soluble in acety1acetone, a'ndseparating the resulting liquid phase from any remaining undissolvedresidue. The amount of the noble metal which dissolves in theacetylacetone, relative to the total amount of the metal in thecomposite, provides a measure of the hydrocarbon conversion activity ofthe composite.

In one embodiment of this invention, a composite comprising a refractoryinorganic material soluble in acetylacetone is treated with a fluidreagent capable of converting the metal to a form substantiallyinsoluble in the oxide, sulfur dioxide 3,169,831 Patented Feb. 1 6, 1965acetylacetone in an amount and fora time suflicient to convertsubstantially. all of the metal to such a form.'

The composite is then contacted with acetylacetone'in a quantitysuflicient to dissolve substantially all of the refractory inorganicmaterial in the acetylacetone. The resulting solution of the material inacetylacetoneis separated from the undissolved residue which containssubtitania, zirconia and, the like. Alumina dissolves readily.

in acetylacetone, while silica dissolves relatively slowly. The presenceof any material insoluble in acetylacetone does not impede thedetermination of hydrocarbon activity of a composite by the method. ofthis invention, because it is not necessary for that purpose that thematerials with which the noble metal is admixed be soluble inacetylacetone. U t

This invention is particularly applicable to the determination ofhydrocarbon conversion .activity of platinum on alumina catalysts andthe recovery of platinuintherefrom; These catalytic composites may havebeen made by cogelling an alumina hydrosol, orv by impregnating solid-alumina,with a platinum compound such as a platinum-halog'en acid or anamine, halide or sulfide of platinum. I The"catalystmaycontainminor.amounts of one or more halogens; v i i I Whenseparating a noble me-tal from composite of,

which it is a constituent, the composite is treated ,with a fluidreagent capable of converting the noblemetal to a form substantiallyinsoluble in acetylacetone. :Thi s treating step is desirable in orderto'separate substantially all of the noble metal from" the supportingmaterial, inasmuchas' it is known, with particular reference toplatinum-aluminacatalysts, that varying proportions of the noble metalmay be present in a form which is soluble in acetylacetone.The-selective solvent power. of acetyl acetone for different forms ofnoble metals is used in the hereinafter-described processing ofcomposites for the determination of hydrocarbon conversion activity. I

The reagent used to convert the noblemetal to a form insoluble inacetylacetone ,may be either a gas or a liquid. Examples. of suitablegases and hydrogen sulfide; examples. of suitable liquid reagents areformaldehyde, formic acid, hydroquinone and aqueous solutionsofarrnnonium formate.

The'concentration of the reagent may vary over wide limits dependingupon the reagent used. It is preferable when using hydrogen thatitbepr'esent in an amount from about 50 to 100 percent of the gasflstream.A par ticularly suitable hydrogen-containing gas forpurposes of thisinvention is a catalytic reforminghydroge'n recycle gas which normallycontains to.85 percent hydrogen and 15 to 25 percent light hydrocarbons.When carbon monoxide, sulfur dioxide or hydrogen sulfide is used as thetreating reagent, its concentrations may range from about 2 percent onup to a substantially pure gas stream. A flue gas containing 2 to about"20 percent carbon monoxide is a particularly suitable treatingreagent.

The concentration of the liquid treating reagents may also vary over awide range. Formicacid may be used' are hydrogen, carbon monl dependingupon the reagent. v I

' amount of reagent is that which will convert allthe noble V Anaqueoussolution containing from about to about SOWeight percent ammoniumformate'is" also suitable. The amountof treating reagent to be used alsovaries In theory, .the minimum metal to themetallic sta'te, o'r,'ii1 thecaseof s ulfur con- 'taining reagents, the corresponding sulfidei. Ithas been found, however, that to' assure complete conversion of thenoble metalto a form which is insoluble in acetylacetone that from 2 toabout .20 times the minimum theoretical amountsjhould be usedwhenworking with liquid reagents liquid solvent comprising acetylacetone in,either the keto l "and from 10 to 11,000 times the theoretical minimum,pref- V erably ZS'tQSOOtimes and advantageously 50to'25i) time's,

when working with gaseous reagents. For treating a given composite,a'greater excess is needed of a gaseous reagent than of a; liquidreagent because'of contacting problems.

The temperature at which the composite is treated also 7 depends uponthetreatin g reagent. When using gasesgthe 1 treatmentlshould be doneata temperature from about 700" to about l350 F;, preferably from about900 to about 1300v F'." Carbon monoxide, hydrogen sulfide and sulfurdioxide convert the noble metal to a form insolublein acetylacetonefaster at agiv'en temperature than does by .drogen, and for this reasonit is desirable to use a treating temperature of aboutllOO to 1300 F,when'using hydrogen, whereas "a, temperature; of about 900 to 1000'", F.

gives asatisfacto'ryrate of conversion with the other gases.

When liquid treating reagents are-used, the temperature may vary fromabout ambient to a temperature somewhat below the boiling point of theliquid, e.g., -with a formic acid solution from about 5010 about 200 F;,advane tageously at a temperature between about 150 to 200 F,

tone. When used for contacting a composite in the method of thisinvention, the term acetylacetone means a form (CH COCH -COCH or the enoform (CH COH=CH-COCH Generally both the keto and eno forms ofacetylacetone are present in the acetylacetone sold commercially. Theacetylacetone sol-- vent should preferably contain 50 weight percentormore of acetylaeetone, and advantageously about 90 95 weight percentacetylacetone. 'Other constituents such as acetone, acetic acid,ethersand water; may be present in the solvent without impairing itsutility for this invention.

About 2 to parts of acetylacetoneto 1 part'oi com posite, wet basis,preferably 3 to 15 parts of acetylacetone, and advantageously 5 to' loparts ot acetylacetone, is used when contactin'g a composite in thedetermination of hydrocarbon activity or when separating a noble metalfrom the composite. The amount of acetylacetone used relative 'to theamount of composite refers'to acetylacetone solvent containing about90=95weight percent acetylace 7 tone. If the acetylacetone content ofthe solvent used is less, the amount :of solvent used shouldbeinc'reased proportionally. V p e I V 7 The contacting'of the compositewith acetylacetone may be done at atmospheric pressures as well as athigher pressures.

The temperature is' preferably maintained between ambient and theboiling point of acetylacetone,

The tinie during which the composite must be'treatedg withithe reagentvaries fromabout'OJ to about 24 hours.

This depends in part on the" reagent used, thetemperature and? the size"of the composite particles. ,With liquid reagents. the treating timeneed only be a few minutes to about-anhour. With dilute carbon'monokideat a tem .peratureof about 900 to 1,000? R, the treatment'should.

:last from about 0.5 to about Shouts. A somewhat longer timeis desirablewhen using hydrogen.

' A wide'range of pressures maybe used; varying from V atmosphericonupwards. Although pressures above atmospheric do not greatly increasethe rate at which the, platinum'is converted to a forminsolubl'e inacetylacetone when treating with liquidrea'gents, above-atmospheric pressures are advantageous althoug'h 'not necessary when'usinggaseous'r'eagentsL For instance, a treatment with carbon monoxidecontaining flue gasro r hydrogen recycle gas may be conductedat apressure in the range normally used for catalytic reforming, 'e.g., fromabo'ut200 to about 800 fp.s.i.g. Higher pressures are also suitable. u-

Thesize of the composite particles being treated affects No. 10 sieve,advantageouslytorpass through a sieve (see ASTM specification Ell-58T).a

' about 139C. The'contac ting is advantageously done by refluxing atatmosphericpressure. The dissolvingof the refractory inorganic materialand any noble metal in a form soluble in .acetyla'cet one proceedsrapidly even at room temperatures, and is normally completed'in frombetweenlfminute to about lhour;

V b The time required for dissolution may be reduced by having firstground or crushed'the composite before contacting it with'acetylacetone, by agitation during the contacting step, and also byrefluxing; 1 7 After the refractory inorganic material has beendissolved by contacting with acetylacetone, the resulting liquid phase,which contains acetylacetone and the refractory "material, is separatedfrom thefremaining undissolve'd residue by means of decanting, filteringor centrifuging.

The residue may optionally'be washed with chloroform, j

low boiling aromatics, 'ketones, ethers or hydrocarbon acids. When awashed'solvent is used on the re'sidue,t-he 'solventis preferablywarmed'to a temperature 'wit hinAO? F. of its boiling point;

;, Theresidue contains, substantially all of the noble metal originallyin the composite. The noble metal in the residue is either in metallicform or,when.hy'drog'en sulfide or sulfur dioxide has been used astreating reagents, as a sul- Possibly some of the noble metal is alsopresent a combined in a complex form which is readily destroyed byconventionalmethods ofplatinum refining. 7 'In, some in- V stances thenoble metal will be sufliciently puretofltbe used without furtherrefining. 1 However, inasmuch as thepur;

"Inasmuchas thetre'atment may'be done on particles up j v to a crosssectional diameter of inch, it is sometimes de- 7 sirable, in respect ofcatalytic composites, to conduct the treatmentwith a gas while thecomposite is in a reaction zone, such-asja fixed or fluid bed refiningunit. Use of carbon monoxide containing flue gas, or hydrogen recyclegas, with orwithoutthe addition of Zto 5 percenthydro gen sulfide, isparticularlyg'suitable when treating a coma posite while it is stillin areaction zone. The treating step should'be: subsequent to anoptionaljstep of burning from the composite any carbonaceous depositsaccumulated,

thereon during use. I I I I After'the noble metal has been converted toa form insoluble in acetylacetone, the refractory inorganic material 7is dissolved by contacting the composite withacetylaceycatalystma'nufacture.

ity specifications for platinunifare generally stringene'it'is i usuallyadvisable to further purify platinum in the residue such as by;dissolving in "aqua regia landfsubsequently sep arating therefrom'j a'purep'latinum compound. .Alterna; tively the solution of platinum inaqua regia may becorii verted to aqueous .chlo'roplatinic acid solutionfor use Whenfu'sing the method of been-treated as a part of the processwith a fiuidrea gent capable of converting the noble metal to'a forrn'substantially insolublein acetylacetone; The composite is -pref-' erablyalthough notanandatorily ground or' crushedjprior to contactingWithFacetyIacet ne in ordertot-reduce the contacting time necessary toassure tlle substantially completed dissolution of any iof the noble,metal which, is .in

7 this inventionfor the pur? pose of determining'the hydrocarbonconversion' 'activity of a noble metal containing catalytic:composite,'.amodi fic'ation'of the above-described procedure is used.The composite iscontacted with acetylacetone withouthaving a formsoluble in acetylacetone. The contacting of the composite withacetylacetone is done as hereinabove described. The time of contactingmay range from a few minutes to, preferably, several hours, and thecontacting is preferably done by refluxing the acetylacetone solution,in order to assure complete dissolution of the acetylacetone-solubleform of noble metal.

After the contacting step is completed, the liquid phase is separatedfrom the remaining residue. The residue is preferably washed one or moretimes with the above-- described solvents. Diflerent solvents may beused in succession if desired.

The hydrocarbon conversion activity of the composite is determined fromthe amount of the noble metal dissolved in theacetylacetone relative tothe total amount of the noble metal originally in the composite. Theamount of noble metal so dissolved may be determined directly byanalysis of the liquid phase solution which Was separated from theresidue. It may also be determined by the ditference between the amountof noble metal originally in the composite and the amount of the noblemetal remaining in the residue. The amount of noble metal in theoriginal composite or in the residue may be determined by conventionalwet chemical analyses, or by spectrophotometric methods, such as thefollowing method described with respect to platinum. Herein the startingmaterial, either the composite or the abovedescribed residue, isdissolved in aqua regia, following which the platinum is converted tochloroplatinic acid by repeated drying of the solution to wet salts andthen dissolving in HCl. Formic acid is added to convert any nitrates tooxides of nitrogen, which are released as gases. A 20 percent solutionof stannous chloride is then added to the chloroplatinic acid solutionto develop the color necessary for platinum determination byspectrophotometric means.

The total amount of noble metal in the composite may also be determinedby treating an aliquot of a composite with a fluid reducing reagentcapable of converting all of the noble metal to a form substantiallyinsoluble in acetylacetone, contacting with acetylacetone, separatingthe resulting liquid phase from the remaining residue, and determiningthe amount of noble metal in the residue, all as described hereinabove.

A noble metal-containing solution of acetylacetone, such as is derivedwhen determining hydrocarbon conversion activity, may be used whenpreparing a new catalytic composite. This may be done by evaporating ordecomposing the acetylacetone, converting the noble metal to a formsuitable for addition to a catalyst-supporting material, andimpregnating that material. It may also be done by separating the noblemetal, as by precipitation as a sulfide, from the acetylacetonesolution, converting the sulfide to a form suitable for addition to afresh catalyst-supporting material, and then impregnating that material.In either situation the noble metal or its sulfide may be converted to asuitable form by treating with I titles or below, followed byevaporation under vacuum of the acetylacetone and ultimately drying andcalcining.

Examples A series of tests was made to demonstrate this invention, usingfour platinum supported on alumina catalytic composites prepared asfollows. Composites A, B and C were prepared by cogelling a'sulfidedchloroplatinic acid solution with a Heard-type alumina hydrosol, and

drying and calcining. Composite D was prepared by gelling, drying andcalcining a Heard-type alumina hydrosol, then impregnating the calcinedalumina with an aqueoussolution ofchloropla-tinic acid and aluminumchloride, and again drying and calcining. Theplatinum contents ofComposites A, B, C and D were, respectively, 0.578, 0.594, 0.576 and0.178, weight percentage. All the catalysts were in the form of A" x Vs"pellets.

In tests to determine the fractions of platinum which were soluble inacetylacetone, a sample weighing approximately 5 grams of the compositeunder consideration was ground to pass a 60. mesh ASTM sieve. The.ground composite and about 50 milliliters of commercially availableacetylacetone were placed in a glass reflux distillation column, and theacetylacetone was refluxed at atmospheric pressure for about one hour.vThe dissolving of the alumina support into the acetylacetone Wasgenerally complete in about five minutes or less.

The resulting liquid phase solution of alumina and acetylacetone,containing in these tests some platinum, was cooled to about roomtemperature and filtered throughWhatman No. 42 filter paper to separatethe liquid phase solution from any remaining solid residue;

The residue remaining on the filter paper was then washed one to threetimes with 25 milliliter portions of chloroform heated to a temperatureof between and F.

The platinum in the residue was determined by dissolving the residue inaqua regia, following which the platinum was converted to chloroplatinicacid by repeated drying of the solution to a wet salt and thendissolving in hydrochloric acid. Formic acid was added to convert anynitrates to oxides of nitrogen, which were released as gases. A 20percent solution of stannous chloride was then added to thechloroplatinic acid to develop the color necessary for platinumdetermination by spectrophotometric methods.

The platinum content of the liquid phase was determined by diiferencebetween the platinum originally in the composite and the platinum in theresidue, all being expressed as a weight percent of the originalcomposite.

Aliquot samples of Composites A, B and D, in the form of /s" x Vscylindrical pellets were tested in a bench scale reforming pilot planthaving a 50 milliliter reactor. The feed was a Mid-Continent naphthahaving an API gravity of about 55, boiling between about and about 400F., and containing about 50 percent parafiins, 40 percent naphthenes,and not more than 1 percent olefins, With the remainder being aromatics.The reforming conditions used were a block temperature of 930 F., apressure of about 200 p.s.i.g., and a weight hourly space velocity ofabout 2. Hydrogen was mixed with the feed at a rate of about 5,000s.c.f. per barrel of naphtha. From the resulting reformate productinspection tests and the reforming conditions used, the relativeactivities of the catalysts in question were calculated as the quantity,expressed as a percentage, of an arbitrarily chosen standard referencecatalyst required to produce a C reformate fraction having the samoctane number under the same test conditions.

The results of the above-described procedures are summarized in thefollowing table:

Platinum Soluble in Acetylacetone Composite Relative Wt. per- Wt. per-Activity cent of cent of Catalyst Total Platinum These data demonstratethe relationship between the fraction of the total platinum in thecomposites which is soluble in acetylacetone, and the relative activityof the composites.

Using the above-described processing technique, 50 percent of theplatinum in Composite C was found to be soluble in acetylacetone. About400 grams of Com- -posite C in a glass reactor was then treated at about1300 F, by passing through the reactor aboutone liter per hour ofhydrogen-atatmospheric pressure for about 16 hours. An aliquot weighingabout -1 gram of the measure of; the hydrocarbon conversion activity ofsaid thus treated catalysttwas ground and refluxed for about six hoursin 25 milliliters of acetylacetone. Thesolution was cooled to about roomtemperature and filtered in order touseparatethe resulting ,liquid'phasesolutions of acetylacetone and alumina from the platinum-con-v plicationS.N. 15,035, filed March 15,1960.

Having described the invention, What is claimed is:

l. A method for determining the hydrocarbon conversion activity of acatalyst comprising a noble metal and a refractory inorganic supportwherein the total amount of said metal in said composite isdeterminable; I

which method comprises contacting said catalyst with acetylacetone for atime sufiicient to dissolve in said acetylacetone any of said metalsoluble therein, separating the resulting liquid phase from anyremaining undissolved residue, and'determini'ng the amount ofsaid metalwhich dissolved in saidacetyl'acetone, whereby the amountof said metalso dissolved, relative to the totalamount of said metal in saidcomposite, provides a a Cl catalyst; we a V V l 2. The method of claim 1wherein said "contacting comprises refluxing said composite in saidacetylacetone. 3. The method of claim lwherein said residue is washedwith an organic solvent; 4. A method for determining the hydrocarbon conversion activity of a catalyst comprising a noblern'etal and arefractory inorganic support, which method cornprises determining in afirst aliquottofsaid catalyst the total amount of said metal in saidaliquot, refluxing a second aliquot of said composite with acetylacetonefor atime sutficieut to dissolve in said acetylacetone any/of saidmetalv soluble therein, separating theresulting liquid phase fro-manyremaining undissolved residue, and de- 7 termining the amount of saidmetaliin said residue, where by the dilference, relative to said totalamount, between v the amount of said metal in said residue from saidsecond aliquot and said total amount provides a measure of thehydrocarbon activity of said catalyst.

References Cited inthe file of this patent I UNITED STATES PATENTS {p IGehauf et al; May 5,

2,928,792 Bertolacini Mar; 15, I960 2 ,'9 5,4s3 V Harlan et al. Dec. 20,1960 V r 1 FOREIGN PATENTS 294,082 Great Britain Nov. 5,1958

OTHER REFERENCES, Chemical Abstracts 53, 129m (1959

1. A METHOD FOR DETERMINING THE HYDROCARBON CONVERSION ACTIVITY OF ACATALYST COMPRISING ANOBLE METAL AND A REFRACTORY INORGANIC SUPPORTWHEREIN THE TOTAL AMOUNT OF SAID METAL IN SAID COMPOSITE ISDETERMINABLE, WHICH METHOD COMPRISES CONTACTING SAID CATALYST WITHACETYLACETONE FOR A TIME SUFFICIENT TO DISSOLVE IN SAID ACETYLACETONEANY OF SAID METAL SOLUBLE THEREIN, SEPARATING THE RESULTING LIQUID PHASEFROM ANY REMAINING UNDISSOLVED RESIDUE, AND DETERMINING THE AMOUNT OFSAID METAL WHICH DISSOLVED IN SAID ACETYLACETONE, WHEREBY THE AMOUNT OFSAID METAL SO DISSOLVED, RELATIVE TO THE TOTAL AMOUNT OF SAID METAL INSAID COMPOSITE, PROVIDES A MEASURE OF THE HYDROCARBON CONVERSIONACTIVITY OF SAID CATALYST.